When using a print/flash/print method, ink can dry out in the open portions of the screen. Over-flashing or over-heating the ink during flashing often causes this problem.
Plastisol ink only needs to feel dry to the touch to be considered flashed.
Over-flashing not only takes more time, but also can create issues with intercoat adhesion, making it difficult for inks printed on top of the white underbase to stick. In addition, if the ink is too hot and isn’t given enough time to cool, laying the screen down on top of the heated print could partly cure ink that is in the screen, thus clogging the mesh.
Using a tight mesh with proper off-contact also can help keep the ink in the screen from over-heating. The proper off-contact assures that the screen peels away from the print as the squeegee passes over, thus minimizing contact with the heated print.
Kieth Stevens is the Western regional sales manager for International Coatings. He has been teaching screen printing for more than 10 years and is a regular contributor to International Coatings’ blogs. For more ink tips and information, visit iccink.com and read the company’s blog at internationalcoatingsblog.com.
